Railway signaling system



p 17, 1929- H. A. THCMPSON 1,728,516

RAILWAY SIGNALING SYSTEM Filed March 20, 1928 INVENTOR; H-H.Thom, son,

Patented Sept. 17, 1929 UNITED STATES UNION swrrorr a} SIGNAL coMrA Y, IPORATION or PENNSYLVANIA "swIssvALE, Jrn NsYLvANIA, A con,

RAILWAY SIGNALING SYSTEM Application filed March 20, 192smsena11vo. 263,119.

My invention relates to railway signaling systems, and particularly to systems of the type known as three-block indicationsignal ing. I One feature of my invention is the provisionof a signaling system of this character which avoidsthe necessity for line wires. v I 1 I will describe one form ofjsignaling system embodying my invention, and'will then point out the novel features thereof inclain'is.

The accompanying drawing is'adiagrammatic view showing one form otsignaling system embodying my invention. Referringto the'drawing, the' reference characters 1 and l designate the 'track rails of arailwaytrack along which trafiic normally moves in the direction indicated by the arrow. These rails are divided by insulated joints Qintoa plurality of blocks, of which o'nly'three are completely illustrated in the drawing,these blocks being designated C-D, D--E and EF, respectively. i Each block is provided with a track circuit comprising a track relay designated by the reference cha'racterT with an'exponent corresponding to the location, which'relay is responsiveto the polarity of the track circuit current flowing in the track rails, as well as to the presence and alOSBDCB Of such current. That is tosay, each relay comprises a contact 18 which occupies its intermediate position when the relay is de-energizech and which swings to the 'right-hand position or the left-hand position according as the relay is energized in the reverse or the normal di rection. Track circuit current is supplied to the rails of'each block in the manner hereinafter explained.

Associated with each track relay are three slow-releasing relays designated by the reference characters X, Y and Z, respectively, with exponents corresponding to thelocationsi Eachrelay X is supplied with current when the associated track relay T is deenergized, that is, when the back contact 18 18 of this track relay is closed. Each relay y Y energized when the associated track relay is energized in the reverse direction, that is, when contact 18--l8 is closed. Each relay Z is energized when the associated track relay is energized in the normal direction, that is, when its contact 18-48 is closed. The circuits for the slow-releasingielays will be. obvious'from the drawing without further explanationyitybeing understood that thereference characters B and O. designate HOWARD A. THOMPSON, or EDGEWOODBORO'UGH,'1?ENNSYLVANTA, AssrGNoa To THE I a or the terminals of'a 'suitable source of current I for energizing these relays. a

The supply of track circuit current for eachblock' is controlled by the relays X,'Y and Z of the blo'cknext in advancaas Well as by afcoding device designated by the reference character A with an exponent cor esponding tothe location. Each coding'de; vice A '15 provided with a 'circuit which passes fromterminal B of a suitable source of current, through the winding of the cod ing deviceand a back I I v p I the" coding device to terminal 0 of the same source of current. It ,follows that each coding device A' is constantly operating to periodically open its back contacts and close its front contacts. p n p Each block is provided with a signal designated by the reference character S with an exponent correspondinglto the location, each of which signals, as [here shown, is of the four indication type comprising two sema-' phore arms 3 and 4. 1 When these'arms are both horizontal, the signal indicates stop, Whenthe upper arm is in the 45 position and the lower-arm'is horizontal (see signal SE),

the s gnal indicates approach restr cted.

When. the upperarm is in the L5 position and thelower armis in .the'90- position (see signal S the signal indicates.approach. When 'the upper arm is in the 90? position and the lower arm is horizontal (see signal) S hthel'signal indicates clear. p

q The, operation of the system isas follows: The block immediately to the right-of point F is occupied-by a car or train represented by anaxle and pair of wheels W, so thattrack relayJTFis' de-energized, with the resultthat rela X is energized and relays Y and Z? areliiotht'op'en; 'All of the circuits for si'g nal S areopen, so that this signal indicates stop. Track circuit current is now supplied to the rails of b.10ck-EF from a bat contactf5 controlled by tery G the circuit being from the middle point of this battery, through wire 19, lower rail 1, relay T upper rail 1, wire 20, front point of contact 8 of relay X back point of contact 10 of relay Y back point of con tact 13 of relay Z wire 23, and back point of contact 7 of coding device A to the lower terminal of battery G The current which is thus supplied to the track rails of block E-F- is of reverse polarity, and is periodically interrupted due to the periodic opening of back point of contact 7 of the coding device A Track relay T is therefore periodically energized in the reverse direction, so that its back contact and its reverse contact are alternately closed. Relays X and Y are therefore alternately. supplied with current, and the slow-releasing characteristics of these relays are such that their front contacts remain closed and their back contacts remain open as long as track relay T 3 is operating in the manner specified, The circuit forarm 3 of signal S is now closed, this circuit being from terminal B, through front contact?) of relay XE, front point'of contact 11 of relayfY wire 25, and the operating mechanism of arm 3 to, terminal 0. The other circuits for signal S? are, however, open, and so this signal gives the approach restricted. indication. Y The track circuit for block D-E is from the. middle point of battery G through wire 19,-rail 1%,relay T rail 1, wire 20, front point ofcontact 8 of relay X front point of contact 10 of relay YE,

I back point of contact 14 of relay Z wire 21 and front point of contact 6 of coding device A to the upper terminal of battery G It follows that periodically interrupted current of normal polarityis supplied to the rails of section DE, with the result that relays X and Z are closed but relay Y is open. 45 circuit for the upper arm 3 of signal SP is closed, which circuit is from terminal 13, through contact 9, of relay X back contact 12 of relay Y front. contact 17 of relay Z wire 25, andthe operating mechanism of armB to terminal 0. The circuit for arm 4 of signal S is also closed, this circuit being from terminal B, through front contact 9 of relay X back point of contact; 11 of relay Y front contact 16 of relay Z9, wire 24:, and

' the operating mechanism of arm 4 to termiun o. It follows thatfsignal S gives the approach indication. Theifilfack circuit for bloclr C-D. is from the middle 'poin t of batteryG through wire 19, rail lg relay T m l ire 9 irontppint fwn ast 8 s 1am at k r i i o ntes 0 r a treat. rle ntet c ntact 3; of rie1ay. ;W 22; m a th u h the a p tof n if of cod 1 g device" A? to the upper terminal earne t, tlllicug f i fi reie 1 new of h s d r e to e loyverterminalofbattery, It follows, that an t me that. t e ba ai o Contact 6 site polarity is supplied to the track rails.

In other words, the current supplied to the track rails of block C-D is alternately of normal and reverse polarity, with the vresult that track relay T is alternately energized in the normaland the reverse direction, so that all three relays X Y and Z are closed. The circuit, for arm 4 Of Signal S is open at the back point of contact 11 of relay Y so that this arm is in the horizontal position. The 45 circuit and the circuit for arm 3 are both closed, however, so that this arm is in the 90 position. The 45 circuit is from terminal B, through contact 9, front point ofcontact 11, wire 25, and the operating mechanism of. arm 3 to terminal 0. The 90 circuit is from terminal B, through front contact 9 of relay X front point of contact 11 of reI-ayY front point of contact 15 of relay Z wire-26, and the operating mechanism of arm 3 td terminal 0. It follows that signal S gives the clear indication. The track circuit for the block next in the rear of point C is also supplied with current of alternately normal and reverse, polarity, the circuit being from the middle point of battery G through wire 19, rail 1, the track relay, rail 1, wire 20, front point of contact 8 of relay X front point of contact 10 of relay Y front point of contact 14; of relay Z wire 22, and then through the back point of contact 6 to the upper terminal of battery G or the front point of contact 7 to the lower terminal of battery G Reverting to the apparatus at point F, it will be noted that relay X is closed, and that periodically interrupted current if reverse A polarity is supplied to the rails of section E,F. If relay X or its energizing circuit should fail, periodically interrupted current of reverse polarity will still be, supplied to the rails of block E F, the circuitbeing from middle point of battery G through rail 1 relay T rail 1 wire 20,back point of contact 8 of relay X wire 23, and back pointof contact 7 of the coding device A to the lower terminal of battery G One advantage of a system embodying my invention, is, as pointed out, that it avoids the necessity for line wires. Another advantage is, that it is immune to false clear signals due to foreign currents.

Although have herein shown and described only one form of system embodying my invention, it is understood that various changes and modifications may be made thereinwithin the scope of the appended claims without departingfrom the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track divided into'blocks, a track relay for each block responsive to reversalsof the poblock next in the rear whereby it the latter block is unoccupied its track relay is periodically energized in the normal direction, means operating when the track relay for a given block is periodically energized in normal direction and alsowhen it is alternately energized in normal and reverse directions to supply current of alternately normal and reverse polarity to the rails of the block next in the rear whereby it the latter block is unoccupied its track relay is alternately energized in normal and reverse directions, andsignals for the blocks controlled by said track relays.

2; In combination, a stretch of railway track divided intosblocks, a track relay for each block responsive to reversals of the polarity of current in the rails of the block, three slow releasing relays for each block, a circuit for the first slow-releasing relay closed when the associated track relay is de-energized, a circuit for the second slow-releasing relay closed when the associated track relay is energized in the reverse direction, a circuit for the third slow-releasing relay closed when the associated track relay is energized in the normal direction, means operating when all" three slow-releasing relays for a given block are open and also when the first relay is closed and the second and third are open to supply periodically interrupted current of reverse polarity to the rails of the block next in the rear whereby if the latter block is unoccupied its track relay is periodically energized in the reverse direction and its first and second slowreleasing relays are closed but its third is open, means operating when the first and sec ond slow-releasing relays for a given block are closed and thethird is open to supply periodically interrupted current of normal polarity to the rails of the block next in the rear whereby it the latter block is unoccupied its track relay is periodically energized in normal direction and its first and third slowreleasing relays are closed and its second is open, means operating when the first and third slow-releasing relays as well as when all three slow-releasing relays for a given block are closed to supply current of alternately normal and reverse polarity to the rails of the block next in the rear whereby if the latter block is unoccupied its track relay is alternately energized in normal andreverse directions and all three of its slow-releasing relays are closed,and signals tor the blocks controlled by said slow-rcleasing relays.

3. In combination, a stretch of railway track divided into blocks, a track relay for each block responsive to reversals of the po larity of current in the rails of the block,

means operating when the track relay for a I given block is de -energ zed to supply periodicallyint'errupted current of reverse polarity to'the rails of the block next in the rear whereby the track relay for the latter block is periodically energized in reverse direction the block is unoccupied, means operating when the track relay for a given block isperiodically energized in the reverse direction for supplying periodically interrupted current o'f normal polarityto the rails of the block neXt'in the rear whereby it the latter block isunoccupied its track relav is periodically energized in the normal direction, means operating when the track relay for a givenblock is periodically energized in normal direction and also when it is alternately energized in normal and reverse directions to supply currentofalternately normal and reverse polarity to the rails of the blockinext in the rear whereby if the latter block isunoccupied its track relay isalternately energized in normal and reverse directions, a signal for each block, and means for causingeach signal to'give the approach restricted indication when the associated ,track relay is p'eri r,

odically energized in the reverse direction, the approach indication when the associated trackrelay is periodically energized in the normal direction, and the clearindication'when the associated track relay is alternately energized in normal and reverse directions.

4*. In combination, a stretch of railway track divided into blocks, a track relay for each block responsive to rcversalsof the polarity of current in the rails of the block, three slow-releasing relays for each block, a circuit for the first slow-releasing relay closed when the associated track relay is de-energized. acircuit for the second slowreleasing, relay closed when the associated traclcrelay is' cnergized in the reverse direction, a circuit for the third slow-releasing relay closed when the associated track relay is energized in the normal direction, means operating when all three slow releasing relays for a given bloclc are open and alsowhen the first relay is' closed and thesecond and third are open to supply periodically interrupted current of reverse polarity to the rails of the block next in the rear whereby it the latter block is unoccupied its track relay is periodically energized in the reverse direction and its firstand second slow-releasing I operatingwhen' the first and second slowreleasing relays for a given block areclosed and the third is open to supply periodically interrupted current of normal polarity to the rails of the block next in the rear Whereby if the, latter block is unoccupied its track relay is periodically energized in normal direction and its first and third slow-releasing relays are closed and its second is open, means operating when the first and third slow-releasing relays as well as when all three slow-releasing relays for a given block are closed to supply current of alternately normal and reverse polarity to the rails of the block next in the rear whereby it the latter. block is unoccupied its trackrelay is alternately energized in normal and reverse directionsand all three of its slow-releasing relays are closed, a signal for each block; and means for causing each signal to give the approach restricted indication when the first and second associated slow-releasing relays are closed but the third is open, the approach indication when the first and third associated slow-releasing relays are closed but the second is open, and the clear indication when all three of the associated slow-releasing relays are closed.

5. In combination, a stretch of railway track divided into blocks, a track relay for each block responsive to reversals of polarity of the current in the rails of the block, means for at times supplying the rails of each block with periodically interrupted current of reverse polarity and at other times with periodically interrupted current of normal polarity and at still other times with current of alternately normal andreverse polarity, three slow-releasing relays for each block, a circuit for the first slow-releasing relay closed when the associated track relay is de-energized, a circuit for the second slows, releasing relay closed when the associated track relay is energized in the reverse direction, a circuitlfor the third slow-releasing relay closed when the associated track relay is, energized in the normal direction, and signals for the blocks controlled by said slow-releasing relays.

6. In combination, a stretch of railway. track divided into blocks, a track relay for each block responsive to reversals of polarity of the current in the rails of the block, means for at times supplying the rails of each block with periodically interrupted current of reversepolarity and at other times with periodically interrupted current of normal polarity and at still other times with current of alternately normal and reverse polarity, a

signal for each block; and means for causing each signal to give the approach restricted indication when the associated track relay is periodically energized in the reverse direction, the approach indication when the associated track relay is periodically energized in the normal direction, and the clear indication when the associated track relay is alternately energized in normal and reverse directions.

7. In combination, a stretch of railway track divided into blocks, a track relay for each block responsive to reversals of polarity of the current in the rails of the block, means for at times supplying the rails of each block with periodically interrupted current of reverse polarity and at other times with periodically interrupted current of normal polarity and at still other times with current of alternately normal and reverse polarity, three slow-releasing relays for each block, a circuit for the first slow-releasing relay closed when the associated track relay is deenergized, a circuit for the second slow-releasing relay closed when the associated track relay is energized in the reverse direction, a circuit for the third slow-releasing relay closed when the associated track relay is energized in the normal direction, a signal for each block; and means for causing each signal to give the approach restricted indication when the first and second associated slow-releasing relays are closed but the third is open, the approach indication when the first and third associated slow-releasing relays are closed but the second is open, and the clear indication when all three of the associated slow-releasing relays are closed.

In testimony whereof I afiix my signature.

HOWARD A. THOMPSON. 

